Diagnostic instrument illumination system

ABSTRACT

An illumination beam director for use with a diagnostic instrument having an optical lens system including a camera aperture for observing along an optical viewing axis passing through the camera aperture, and an illuminator including an illuminator aperture for projecting illumination along a first illumination axis passing through the illumination aperture. The light beam director includes a pair of opposed redirecting surfaces which receive the light from the illuminator along a first illumination axis and redirect the light onto a second illumination axis, wherein the second illumination axis is closer to the optical axis than is the first illumination axis to overcome shadowing effects on the viewing axis.

FIELD OF THE INVENTION

This invention relates to diagnostic instruments, and more specificallyto an improved off-axis illumination system for a colposcope forcorrecting shadowing effects induced during an examination procedure.

BACKGROUND OF THE INVENTION

Diagnostic instruments having viewing optics for viewing a target arecommonly known, particularly in the medical field, for conductingdiagnostic examinations. An example is a colposcope which is used bygynecologists to conduct patient vaginal examinations. Typically, thescope is placed a predetermined distance from the patient and pointed ata speculum, which is used to hold open the vaginal cavity in order toallow viewing of the cervix. Light from an illumination source of thecolposcope is projected along an illumination axis with the illuminationsystem being set at an angle off-axis relative to an optical viewingsystem, such as shown in FIG. 2.

A recurring problem is that the presence of the speculum, as well as theoff-axis alignment of the illumination system causes shadowing of theimage being viewed,( ie: the cervix or other intended target), makingexamination difficult, as well as time-consuming to perform. In the samedescribed procedure, shadowing of the viewed image may also occur when aphysician attempts to obtain a culture, or otherwise introduces a probeor swab into the vaginal cavity.

There is a need, therefore, to provide an improved illumination system,particularly for a colposcope, but advantageously for other diagnosticinstruments as well, which reduces the effects of shadowing and allowsmore efficient use of the instrument's optical system.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide animproved illumination system, useful with many diagnostic instruments,but in particular with those using off-axis illumination systems, suchas a colposcope, to improve the efficiency of the instrument.

It is another primary object of the present invention to provide anillumination system which adjustably allows projected light to be betterguided to a viewing area of interest, with reduced shadowing, such as inthe case of when swabs, probes, are used during a diagnostic inspection.

Therefore, and according to a preferred aspect of the present invention,there is provided an illumination beam director for use with adiagnostic instrument having means for illuminating and examining atarget, the instrument having an optical lens system including a cameraaperture for observing along an optical axis passing through the cameraaperture, and an illuminator including an illuminator aperture forprojecting illumination along a first illumination axis passing throughthe illumination aperture, the illumination director comprising:

first light redirecting means situated along the first illumination axisfor receiving light from the illuminator and redirecting the light in afirst direction;

second light redirecting means opposed to the first light redirectingmeans for receiving the redirected light from said first lightredirecting means and redirecting the light along a second illuminationaxis, such that the second illumination axis is closer to the opticalaxis than is the first illumination axis at the first light redirectingmeans.

An advantage in using a beam director as taught by the present inventionin combination with a colposcope as described, is that shadowing effectsinduced by the speculum or other sources extending into the viewing axisduring examination are significantly reduced.

A further advantage is that the presently described beam director, canreduce shadowing without impacting the intensity of incident lightprojected on a particular target.

A further advantage is that the beam director can adjustably compensatefor on-axis shadowing effects, as well as off-axis effects, to allowimproved use of the viewing optics.

These and other advantages, objects, and features will now be describedaccording to the following Detailed Description of the Invention, asillustrated by the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial front perspective view of a video colposcopic systemaccording to the present invention;

FIG. 2 is the side sectional view of the colposcope of FIG. 1 as usedduring an examination procedure;

FIG. 3 is an exploded top perspective view of an illumination beamdirector for the colposcope shown in FIG. 1;

FIG. 4 is a side view of a light redirecting element contained in theillumination beam director of FIG. 3;

FIG. 5 is a side sectional view of the colposcope of FIG. 2, includingthe illumination director in accordance with a preferred embodiment ofthe invention;

FIG. 6 is a partial front view of the colposcope and illumination beamdirector as viewed along the line 6--6 of FIG. 5; and

FIG. 7 is a partial rear view of a front movable portion of theillumination beam director of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion is directed to a preferred embodimentdescribing a colposcopic system for conducting a diagnostic medicalexamination of the cervix. It will be readily apparent, however, thatthe concepts described herein are also applicable to other diagnosticinstruments, particularly those having off-axis illumination systemsaligned relative to a viewing axis. In addition, terms such as "front","rear", "top", "bottom", and "side" are used throughout the course ofthe discussion, but the use of these terms is to provide a frame ofreference for reasons of clarity. These terms should not be limiting tothe manner and form of possible embodiments covered by the appendedclaims.

As shown in FIGS. 1 and 2, there is provided a compact video colposcope10 having a housing 12 made from a lightweight or other suitablematerial which is attached to a supporting fixture 18. The fixture 18 isnot shown in FIG. 2, and is partially shown in FIG. 1. Preferably, thehousing 12 includes a pair of half sections 14, 16 which sandwich anumber of supported components therebetween, the components beingsupported on an internal casing 20. According to this embodiment, thesupporting fixture 18 includes an interfacing handle portion 22,provided at the pivotal yoked end 24 of a vertical pole 26 extendingfrom a base portion (not shown), and having respective bottom and sideretaining portions 28, 30 sized for accommodating the bottom and rearsides 32, 34 of the housing 12 and attachable thereto by use of alocking knob 36. The supporting fixture 18 allows the colposcope 10 tobe used in a variety of supported orientations by selective use ofadjustment knobs 38, 40 and 41 in order to tip, rotate, and raise theattached instrument. Details relating to the attachment of the describedcolposcope 10 and the operation of the supporting fixture 18 areprovided in commonly assigned and copending U.S. Ser. No. 08/748,375,the entire contents of which are hereby incorporated by reference.

According to the described embodiment, the colposcope 10 includes anoptical system 42, including a video camera 44 and a series of linearlyarranged optics, including a front facing optic or lens 46 which arehoused within the upper portion of the housing 12 and define an opticalaxis 48. The video camera 44 contains a CCD imager to electronicallycapture and transmit a viewed image as is known in the art. According tothe present embodiment, the video camera used is a SONY model-EVI-330 or331.

The housing 12 includes a series of control switches 50 for controllinga motorized zooming mechanism (not shown), for focussing the opticswhich are set to focus nominally at approximately 250 mm-300 mm from thefront lens 46, and for activating an electronic green filter (not shown)which removes a portion of the red color from the video image in orderto promote vascular discrimination. The electronic green filter isdescribed in greater detail in commonly assigned U.S. application Ser.No. 08/700,299, Attorney Docket 282172! (Krauter, et al), filed Aug. 20,1996.

The colposcope 10 also includes a self-contained illumination systemwhich includes a light source, in this case a high intensity,subminiature arc lamp 54, which emits white light through a collimatingtunnel 56 having an exiting aperture 58 for projecting illuminationalong a first illumination axis 60. The arc lamp 54 can be accessedthrough a removable portion or lamp door 62 of the housing 12 which issnap-fitted to the assembled half portions 14, 16. The lamp door 62includes a spaced set of slit-like openings 64 for allowing heat to bedissipated from the housing 12, while a similar set of slit-likeopenings 66 are provided in the rear side 34 of the housing 12 inproximity to a cooling fan 68 disposed adjacent the video camera 44. Thearc lamp 54 according to this embodiment is described in commonlyassigned U.S. Pat. No. 5,083,059 (Graham, et al), the entire contents ofwhich are hereby incorporated by reference.

As shown in FIG. 2, the illumination and optical axes 48, 60 converge ata target 70 (preferably the cervix, shown diagrammatically) located apredetermined distance (S) from the front optic 46, with an includedangle θ therebetween. This position is coincidental with the approximateposition of the cervix of a patient and preferably the focal point ofthe front optic 46. According to this embodiment, the angle θ isapproximately 12 degrees.

According to this embodiment, the colposcope 10 includes a singleelectrical receptacle (not shown) in the rear of the housing 12 intowhich electrical connections are made with the components supported bythe internal casing 20, including the video output of the video camera44. The supporting fixture 18 on the other hand, includes a power supply(not shown) attached to the pole 26 and having a set of external ports(not shown) which allow electrical connection to an AC power input (notshown) and a series of peripheral devices, such as a video monitor (notshown) and a video printer (not shown). Each of these features aredescribed in greater detail in co-pending and commonly assigned U.S.patent application Ser. No. 08/748,375, previously incorporated in itsentirety.

As described by the Ser. No. 08/748,375 reference, the power supply (notshown) contains circuitry and cabling (not shown) extending through theinterior of the pole 26 and channeled into the interfacing handleportion 22, and specifically into the electrical connector which thenengages the rear electrical connector of the housing 12, when thecolposcope is attached to the fixture 18. When a power switch (notshown) is activated on the rear of the interfacing handle portion 22,electrical power is applied to the colposcope components from the powersupply (not shown) and the video output is transmitted through theengaged connectors to the power supply (not shown), and is thentransmitted to the attached peripheral devices.

The interfacing handle portion 22 also includes a plurality of remotecontrol buttons (not shown) for controlling the video image produced bythe camera 44.

In use, the colposcope 10 is separably connectable to the interfacinghandle portion 22 of the supporting fixture 18, or another supportingfixture (not shown) as described in the Attorney Docket 281₋₋ 240!reference.

Referring momentarily to FIG. 1, an illumination beam director 72 isshown, which is attached to the front of the housing 12 and over theexiting aperture 58, FIG. 2, of the light collimating tunnel 56, FIG. 2.The director 72 is not shown in FIG. 2 in order to better describe thenormal working operation of the colposcope 10 as follows.

Therefore, referring specifically to FIG. 2, a speculum 51, ofconventional design, is required for colposcopic examinations to holdthe vaginal opening open to allow inspection of the cervix. The speculum51 includes a pair of jaw-like molded plastic portions 53, 55 eachhaving projecting ends which are introduced into the vaginal cavity (notshown). The lower jaw portion 55 is fixed relative to a base portion 49,while the upper jaw portion 53 is pivotally movable to open the vaginalcavity by means of a depending locking lever 59 which engages a set ofradial locking tabs 57 that are a formed part of a yoke 63. This yoke 63slides in a channel 65, shown in phantom, in the base portion 49. Inuse, the speculum 51 can be adjusted to a range of opening positions byselecting the proper locking tab 57, and ratchet step 67 on the baseportion 49, thereby locking the upper jaw portion 53 into a fixedposition.

The upper jaw portion 53 of the speculum 51 provides an opening whichallows light to be freely transmitted without interruption between thetarget 70 and the video camera 44 along the optical axis 48. Thepresence of the base portion 49 and yoke 63, however, produces a partialshadow 75 and full shadow 77 on the target 70 due to the off-axisalignment of the illumination axis 60, darkening a portion of the targetas perceived by the video camera 44. Illumination, of course, isnecessary in order to adequately view the cervix visually.

Reference is now made to FIGS. 3, 5, and 7, in order to first describethe features of the illumination beam director 72, which includes amounting barrel 74 having a cylindrical cross section and is sized forfitting over the light collimator tunnel 56. The mounting barrel 74includes a series of slots 76 along the periphery of the barrel forengagement with tab sections 81 provided on the front ends of thehousing sections 14, 16 which sandwich the director 72 therebetween,preferably during the assembly of the housing 12.

The beam director 72 also includes a front rotatable casing 86 assembledfrom a pair of interconnecting sections 88, 90 which define an interior96 sized for retaining a light redirecting member 98, described ingreater detail below, and including a pair of windows 100, 103, FIG. 6.

When assembled, the front casing 86 includes a ring-like circular rearengagement portion 92 for engaging a front engagement portion 78 of themounting barrel 74. In particular, the front engagement portion 78includes an annular groove 80 and adjacent radial engagement rib 82 forreceiving an annular tab 93 and adjacent radial slot 95, respectively,of the rear engagement portion 92.

The front engagement portion 78 also includes a forward mounting surface84 having a through aperture 97, the mounting surface having aprojecting tab 112 extending therefrom for engaging a partialcircumferential slot 110, FIG. 7, provided on a corresponding rearwardmounting surface 91, FIG. 7, of the assembled front casing 86. Aflexible O-ring 99 is also provided for fitting to the periphery 87 ofthe forward mounting surface 84 to provide means for damping when thefront casing 86 is assembled. When assembled, the O-ring 99 alsoprovides an axial load for the front of the annular tab 93 against therear of the rib 82. In addition, the engagement rib 82 has a radial hole130 provided at the top and at the bottom (not shown) of its rearsurface. A pin 132 is then press fitted into each of these holes 130.

Referring to FIG. 4, the light redirecting member 98 is a prismaticelement made of acrylic or other lightweight clear material and having apair of angled surfaces 102, 104 which redirect the collimated lightfrom the high intensity arc lamp 54 from the first illumination axis 60to a second illumination axis 106.

In assembly, and referring to FIG. 3, the O-ring 99 is first placed overthe forward mounting surface 84 and against a front facing surface ofthe radial engagement rib 82. The periphery 87 of the forward mountingsurface 84 has a width dimension sized for retaining the O-ring 99.

One of the interconnecting sections 88, 90 is then aligned with themounting barrel 74, and is fitted thereto by positioning the annular tab93 and radial slot 95 of the rear engagement portion 92 of the section88, 90 with the annular groove 80 and adjacent radial engagement rib 82of the front engagement portion 78 of the mounting barrel 74.

The light redirecting member 98 is set into the defined interior 96 ofthe remaining section 90, 88 of the front casing 86 which is thensimilarly positioned to attach to the mounting barrel 74. The projectingtab 112 of the forward mounting surface 84 is engaged into the partialcircumferential slot 110, FIG. 7, of the rearward mounting surface 91,FIG. 7, of the front casing 86. The casing 86 is fixedly attached bysecuring the sections 88,90 using threaded fasteners 101 to completeassembly of the director 72. Finally, the slots 76 of mounting barrel 74are placed in the retaining tab portions 81 of the housing 12 forfitting the assembled director 72 to the colposcope housing 12.

Referring to FIGS. 3, 6 and 7, the O-ring 99 provides a frictional forcein order to allow rotation of the front casing 86 about the periphery ofthe mounting barrel 74 after a predetermined mount of torque is applied,the rotation of the front casing being restricted by the partialcircumferential slot 110. At the center rotational position of thecasing 86, the pins 132 engage the split between the two sections 88,90, thereby providing a detent feature as the casing is rotated betweenselected positions, as shown at extreme positions A and C in FIG. 6.

Referring now to FIGS. 3 and 5, the benefits of a colposcope 10 havingthe attached illumination beam director 72 is now apparent. As in thepreceding discussion, a speculum 51 is used to hold open the vaginalcavity. In this instance, however, the presence of the beam director 72causes light passing through the existing aperture 58 of collimatortunnel 56 to also pass through aperture 97 of the mounting barrel 74. Asmost particularly shown in FIGS. 5-7, the illumination beam director 72can be rotated within the range dictated by the engagement of theprojecting rib 112 within the partial circumferential slot 110. In thedetent or center position, the light, shown as arrow 121, FIG. 4, passesthrough an entrance surface 108 of the prismatic member 98, isintercepted by the lower redirecting surface 102 and is reflectedupwardly toward the opposite second redirecting surface 104. Each of theredirecting surfaces 102, 104 has a reflective or mirrored exteriorcoating in order to insure that the light reflects therefrom. The lightis finally redirected through an exit surface 116 and the window 103along a second illumination axis 106 which is closer to the optical axis48 than is the first illumination axis 60. The angle (θ') between thesecond illumination axis 106 and the optical axis 48 is about 7 degrees.The redirected light does not significantly degrade in intensity andprovides sufficient illumination without shadowing of the speculum 51onto the cervix. In this position of the front casing 86, the axis ofthe redirected light is in the plane defined by the axes 48, 60.Rotation of the casing 86 about the first illumination axis 60 from thedetent position (see positions A and C, FIG. 6), causes the axis of theredirected light to shift laterally out of this plane. The illuminationcan thereby pass by an instrument or other object (not shown) which isinserted into the vaginal cavity so as to additionally minimize anyshadowing effects which might be produced.

In addition and as clearly shown in FIG. 4, at least one of the exit andentrance surfaces 108, 116 are angled (β) in order to allow theredirected light to be projected to the same convergence point shown inFIGS. 2 and 5, despite the change in the included angle θ→θ' between theoptical and illumination axes 48, 106. For purposes of this embodiment,a suitable angle (β) is about 5 degrees.

PARTS LIST FOR FIGS. 1-7

10 compact colposcope

12 housing

14 half section

16 half-section

18 supporting fixture

20 internal casing

22 interfacing handle portion

24 yoked end

26 vertical pole

28 bottom retaining portion

30 side retaining portion

32 bottom side of housing

34 rear side of housing

36 locking knob

38 adjustment knob

40 adjustment knob

41 adjustment knob

42 optical system

44 video camera

46 front optic

48 optical axis

49 base portion

50 remote control switches

51 speculum

52 illumination system

53 upper jaw portion

54 arc lamp

55 lower jaw portion

56 light collimating tunnel

57 radial locking tabs

58 exiting aperture

59 locking lever

60 first illumination axis

62 lamp door

63 yoke

64 slit-like openings

65 channel

66 slit-like openings

67 ratchet steps

68 cooling fan

70 target

72 illumination beam director

74 mounting barrel

75 partial shadow

76 peripheral slots

77 fall shadow

78 front engagement portion

80 annular groove

81 tab sections-housing

82 radial engagement rib

84 forward mounting surface

86 front casing

87 periphery

88 interconnecting section

90 interconnecting section

91 rearward mounting surface

92 rear engagement portion

93 annular tab

95 radial slot

96 interior

97 through aperture

98 light redirecting member

99 O-ring

100 window

101 threaded fasteners

102 lower light redirecting surface

104 upper light redirecting surface

106 second illumination axis

108 entrance surface

110 circumferential slot

112 projecting tab

116 exit surface

121 arrow

130 radial holes

132 pins

While the invention has been described with reference to a preferredembodiment, it will be appreciated that various modifications can bemade without departing from the spirit of the invention. Suchmodifications are intended to fall within the scope of the appendedclaims.

We claim:
 1. A diagnostic instrument comprising:a housing; an opticalsystem disposed within said housing; an illumination system adjacentlydisposed relative to said optical system, said optical system having atleast one optical element and a viewing aperture for defining an opticalaxis for viewing a target, said illumination system including a lightsource and an illumination aperture defining an illumination axis toallow illumination to be projected onto said target, wherein saidillumination and said optical axes converge only at a single point fromsaid diagnostic instrument onto said target disposed a predetermineddistance from said housing, said axes having an included angletherebetween, and; means for redirecting at least one of said opticaland illumination axes to reduce said angle without changing the singleconverging point of said axes; wherein said redirecting means aredisposed at an intermediate location along one of said axes.
 2. Adiagnostic instrument as recited in claim 1, wherein said axisredirecting means includes a beam directing element having first lightredirecting means disposed along an initial illuminating axis toredirect light in a first direction and second light redirecting meansfor receiving and redirecting the light along a second illumination axiswherein said second illumination axis forms a smaller angle with saidoptical axis than said initial illuminating axis.
 3. A diagnosticinstrument as recited in claim 2, wherein said beam directing elementincludes a housing having a prismatic element disposed therein, saidprismatic element including a pair of opposing light redirectingsurfaces, in which a first redirecting surface is disposed in said firstillumination axis for redirecting light from said light source in saidfirst direction, and a second light redirecting surface is substantiallyopposed to said first light redirecting axis for receiving andredirecting said light along said second illumination axis.
 4. Adiagnostic instrument as recited in claim 3, wherein at least one ofsaid first and second light redirecting surfaces is angled relative tothe first illumination axis for redirecting the light along the secondillumination axis without changing the predetermined distance at whichsaid optical and first illumination axes converge.
 5. A diagnosticinstrument as recited in claim 2, wherein said beam directing elementincludes means for rotatably attaching to said illumination system toallow rotation of said element about said first illumination axis.
 6. Adiagnostic instrument as recited in claim 5, wherein said beam directorelement includes a mounting section for attaching to said housing, andan adjustable section mounted for rotation on said mounting section,said prismatic member being included in said adjustable section.
 7. Adiagnostic instrument as recited in claim 6, including means forrestricting rotational movement of said adjustable section within apredetermined range of positions.
 8. A diagnostic instrument as recitedin claim 7, wherein said rotational restriction means includes acircumferential slot disposed on either of said mounting section andsaid adjustable section for engagement by a tab disposed on the other ofsaid mounting and adjustable sections.
 9. A diagnostic instrument asrecited in claim 8, including detent means for indicating when saidadjustable section has been rotated to a centered position relative tosaid mounting portion.
 10. A diagnostic instrument as recited in claim 6including damping means for preventing the adjustable portion fromrotating until a predetermined amount of torque is exceeded.
 11. Adiagnostic instrument as recited in claim 10, wherein said damping meansincludes an O-ring disposed between contact surfaces of said adjustablesection and said mounting section.
 12. A diagnostic instrument asrecited in claim 11, wherein said instrument is a colposcope, in whichsaid adjustable section allows redirected light along said secondillumination axis to be selectively shifted laterally relative to saidoptical axis to avoid shadowing of instruments placed in relation to thetarget.
 13. A diagnostic instrument as recited in claim 12, wherein saidillumination system of said colposcope is disposed below said opticalsystem.
 14. A diagnostic instrument as recited in claim 13, wherein saidillumination system is disposed above said optical system.